The present invention relates to a silver halide color photographic photo-sensitive material. More particularly, the present invention relates to a silver halide color photographic photo-sensitive material which is highly sensitive to light, is excellent in storability and is improved in pressure induced desensitization.
Color photography is a process of producing dye images achieved by using a photo-sensitive material comprising a support having thereon photographic structural layers comprising a silver halide emulsion and dye forming couplers. The photo-sensitive material is subjected to development processing with an aromatic primary amine color developing agent, resulting in production of an oxidation product of the developing agent. The dye images are formed by reaction of this oxidation product with the dye forming couplers.
Simplified and rapid color development processing is a strong requirement of the color photographic field and various improvements have been achieved. Advanced faster systems have been developed one after another in a cycle of a few years.
To increase a processing speed requires a further approach to shortening time for each of color development, bleach-fixing, washing with water and drying processes. A method of increasing the processing speed is disclosed in, for example, International Patent Publication No. WO 87/04534. This publication discloses a method of rapid processing by using a color photographic photo-sensitive material comprising high silver chloride emulsion. From the viewpoint of the rapid processing, it would be preferable to use the high silver chloride emulsion.
Such efforts yield a technique of printing images of a color negative on a silver halide color photographic printing paper for high silver chloride printing, which has become a common method for simple and easy production of high-quality images.
The higher contents of the silver chloride in the silver halide emulsion to be used result in a far advance in a development speed. The silver chloride emulsion is, however, found to have a disadvantage of lower photo-sensitivity. With this respect, various techniques and methods are disclosed to improve the photo-sensitivity of such the high silver chloride silver halide emulsion, and thereby to overcome the above mentioned problem.
Under normal conditions for forming grains, silver chloride emulsion grains suitable for rapid processing are cubic in shape mainly having {100} faces. However, various attempts have been made to exhibit some characteristics and performances including high sensitivity that are lacking or unavailable in the cubic grains by means of forming octahedral or tabular grains mainly having (111) faces using various grain growth controlling agents.
In particular, it has been found that highly sensitive emulsion can be obtained with grain growth controlling agents disclosed in JP-A-2-32 (the term "JP-A" as used herein means an "unexamined" published Japanese patent application), JP-A-212639 and JP-A-4-283742.
The present inventor prepared the octahedral and tabular grains mainly having (111) faces by using the above mentioned specific grain growth controlling agent to study and examine availability of a highly sensitive high silver chloride emulsion. As a result, it has revealed that the high silver chloride emulsion formed by using the specific grain growth controlling agent that contains octahedral or tabular grains mainly having (111) faces is highly sensitive but photo-sensitive materials to which the emulsion in question is applied are suffered from a problem of increase of fogging density during a long period of storage. There is a noticeable increase in the fogging density of the photo-sensitive material subjected to the long period of storage when a color developer contaminated with a bleach-fixing solution is used during a continuous color processing. This is a serious problem in practical applications considering a storage period up to when the photo-sensitive material is used, after being prepared, in the field of processing laboratory as well as considering a possibility of change in composition of a processing solution.
As a method of achieving this high sensitivity, for example, JP-A-2-20853 discloses that the high sensitivity can be achieved by means of doping a high silver chloride emulsion with a six-coordination complex of Re, Ru or Os having at least four cyan ligands. JP-A-1-105940 discloses that an emulsion having excellent reciprocity law properties can be obtained without deterioration of latent image stability at a few hours after exposure by using an emulsion containing high silver chloride grains having silver bromide rich regions in which iridium (Ir) is selectively doped. JP-A-3-132647 discloses that a high silver chloride emulsion that contains iron ions contributes to production of a highly sensitive, hard gradation photo-sensitive material of which sensitivity is less affected by fluctuation of temperature or intensity of illumination during exposure, and contributes to reduction of pressure induced desensitization of the material when pressure is applied to it. JP-A-4-9034 and JP-A-4-9035 disclose that such a photo-sensitive material can be obtained that is highly sensitive and is less in reciprocity, and that has good latent image storability with less pressure fogging by using a high silver chloride emulsion that contains a specific metal complex having at least two cyan ligands. JP-A-62-253145 discloses that such a silver halide photographic photo-sensitive material can be obtained that is less affected by the pressure fogging or the pressure induced desensitization and that is suitable for rapid processing by means of containing metal ions in the high silver chloride emulsion having a silver bromide rich phase.
On the other hand, JP-A-2-6940 and U.S. Pat. No. 4,917,994 disclose that increase of fogging of photo-sensitive materials can be restricted by means of adjusting pH of the coating of the materials. In addition, JP-A-2-135338 and JP-A-3-1135 disclose that to keep pH of a coating of photo-sensitive materials at a specific level restricts fogging and change in photo-sensitivity during storage of the photo-sensitive material.
However, none of the above mentioned techniques has led to a method of restricting increase of the fogging density and the pressure induced desensitization of the aforementioned specific high silver chloride emulsions, especially increase of the fogging density after a long period of storage that becomes notable when the color developer contaminated with a bleach-fixing solution is used in a continuous color processing.
Accordingly, an object of the present invention is to provide a silver halide color photographic photo-sensitive material which is highly sensitive to light, is excellent in storability, is improved in pressure induced desensitization.